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Inca's balsa log raft

Theory for Daggerboard navigation


Guara is a steer system and not a keel supplement
- a wind self steering system -


First encounter with balsa rafts

When the spaniards meet the Inca balsa rafts, they were surprised by the cargo they were able to carry - but too the fact, that those rafts were navigated without a rudder, but nevertheless were able to go as close or better to the wind than the Spanish ships. But how that technology worked is still today something of a mystery.

[ img - balsa-Bruning.jpg ] [ img - balsas107a-Bruning.jpg ]
Two GLASS PLATE photos - showing some of the LAST balsas
- in the end of 19th century -
courtesy Brüning Museum, Lambayeque

Guaras work only in the combination of wind and sea
A balsa raft = a Kon-tiki-raft is a raft of balsa-wood-logs with Guaras plunged-in (inserted) between the logs to control that leeway, as every sail-craft has. Guara they called it and Guara is the accepted word for those daggerboards, centerboards, lee-boards, lifting keels, swinging swords - words as all are synonyms for nearly the same - retractable keels. The word Guara is not a Quechua word - it is told to come from a language nearer to Equator.
Another interpretation is, that "Guara" - pronounced 'uara' - simply could be a bad spelling of the spanish word "vara". Vara hold among other the meaning: stick, pole, rod - and that seems more in accordance with a seaman's vocabulario. But look in your own Spanish dictionary.
That seems submitted the same sound interchange as when the English word 'watchman' entered the Spanish vocabulario as 'guachiman' and 'sandwich' as 'sanguche'.

This Guara-system has worked in hundreds of years, even if Thor Heyerdahl had to rediscover it.
Opposite the classic stern rudder as need streaming water to change direction of a boat - a sail powered Guara-raft can turn statically = on the site. It need only water and wind to act.

a principal difference:
Rudder-steering may accumulate a deviation of a course - and need therefore a helmsman
Guara-steering auto-correct a deviation, but work slower
The curved yard is still seen on the photos 70 years later - so it is probably not occasional
Note that the Guaras are concentrated as groups in both ends of the vessel
- that we could interpret, as a Guara-raft don't need more keel in between
[ img - raft1841.gif ]
Drawing from Ecuador 1841

In South America the ship development was different.

They knew the dugouts and expanded canoes, as they used on the rainforest rivers, but not on their Pacific ocean, there they used other means. Their balsa wood is a wonderful material - the lightest wood in the world, and therefor instead of digging out the trunks, they tied more of them together and got a raft with a rather good carrying capacity and impossible to capsize.

A raft of trunks is a fine vessel and could have a long and fat central trunk as stem and keel, but equipped with sail they plunged in some boards between the trunks to obtain a more stable course. Here they discovered the Guara-steering, but not the rudder. They could sail over all the ocean with their heavy loaded, but slow moving crafts, and they were beating so effectively to the wind, that they without greater problems could return to their starting point.

There they were in their development when the Europeans came and took over the control. The Europeans recognized the men of the coast societies as efficient seamen and sailors, but they never understood how the Guaras worked.
For the Europeans the function of Guaras has been a mystery in hundreds of years: Their world far away simply hasn't understood how to use these daggerboards, but nevertheless the South Americans have used them daily on their ocean sailing rafts.

The conditions for any sail-powered vessel were always:
LOW forward resistance together with a HIGH lateral ditto
Guara steering - still something of a mystery

A first Guara explication

[ img - Ulloa-drawing 1748.jpg ]
Balsa drawing from book of Ulloa 1748

The earliest technical description of the function of Guaras is given by the Spanish scientifics Jorge Juan and Antonio Ulloa as in 1736 were joining a French geodesic mission to west coast of South America.
The original Spanish version of their book is from 1748, can be found in Volumen I  page 314-320
The digital extracts presented here are from the later English edition of 1772:  page 181-183
Inside this English 500 pages book, the pages 183, 184 and 185 are giving an exact explication of the function of Guaras.
With the later Guara-troubles in mind it is rather interesting to read this early explication, observing that this knowledge could have saved many 20-century raft skippers from serious troubles.

voyage-frontpage.jpg voyage-183.jpg voyage-184.jpg voyage-185.jpg
pages from book of 1772 - highlighting the text about the Guaras
Transcript of page 182-183:
"Hitherto we have only mentioned the construction and the uses they are applied to; but the greatest singularity of this floating vehicle is, that it sails, tacks, and works as well in contrary winds, as ships with a keel, and makes very little lee-way. This advantage it derives from another method of steering than by a rudder; namely by some boards, three or four yards in length, and half a yard in breadth, called Guaras, which are placed vertically, both in the head and stern between the main beams, and by thrusting some of these deep in the water, and raising others, they bear away, luff up, tack, lay to, and perform all the other motions of a regular ship; an invention hitherto unknown to the more intelligent nations of Europe, and of which even the indians know only the mechanism, their uncultivated minds having never examined into the rationale of it."
- - - -
Transcript of page 183-184:
"Whence it follows, that a Guara being throwed down in the fore-part of the vessel must make her luff up; and by taking it out, she will bear away or fall off.
Likewise on a Guara's being throwed down at the stern, she will bear away and by taking it out of the water, the Balza will luff, or keep nearer to the wind.
Such is the method used by the indians in steering the Balzas, and sometimes they use five or six Guaras, to prevent the Balza from making lee-way, it being evident, that the more they are under water, the greater resistance the side of the vessel meets with; the Guaras performing the office of lee boards, used in small vessels.
The method of steering by these Guaras is so easy and simple, that when once the Balza is put in her proper course, one only is made use of, raising or lowering it as accidents require, and thus the Balza is always kept in her intended direktion."

The arrogant attitude expressed against the indians and their culture could be personal, it could be a common expression of an European culture regarding the indians as subhumans at their service - or it could be deeply ironical against themself. The truth we see today, is that only few of the Europeans have understood the Guara-explication, and that a man as Thor Heyerdahl needed to rediscover the phenomenon, even if he could have learned it in Guayaquil.


Thor Heyerdahl's investigation

When Thor Heyerdahl in his famous sailing lifted up a Guara for repair, he experienced that the raft changed direction. Without intentions, he changed the underwater hull. This discovery caused a subsequent research. Thor Heyerdahl's explication is drawn up after consulting and experiments in the Balsa Raft Society in Guayaquil in Equador, and he furthermore refer to publications of explorers as Humboldt in 1810 and Stevenson in 1825.
cite: "In 1953, Emilio Estrada of Guayaquil arranged for a small test raft to be constructed like the Kon-tiki, of nine balsa logs lashed together and covered by a bamboo deck. Likewise, for navigation, a square sail was hoisted on its usual bi-pod mast in native fashion, and similarly six Guaras were inserted between the logs, two in the extreme bow and two in the stern. No paddles, rudder or steering-oar were carried on the raft, which was launched from the open coast of playas, Ecuador, with a crew of four."
(ref. book: Kon-tiki, p.109).

With 12 sketches as cartoon-strip is demonstrated how a raft, equipped with square sail and Guaras mounted along the main trunk, will react on its Guaras under a static turn all the clock around.

Explication for the strip of sketches
If we want to change course, we have to lift out a Guara in that end, we want to go leeward.
Without hold in water this end will float away with the wind, while the rest of the Guaras will keep their hold in the water.

[ img - thor-Guaras.jpg ]
- and that was what Antonio Ulloa and Jorge Juan had explained 200 years earlier

Balanced leeway with a dinghy:

The experiment in Guayaquil was followed up in Denmark, where a common sail dinghy was equipped with two in-line Guaras /centerboards.
Cite from the book: "Sejlads på en anden måde"
"The new principle - the use of two 'swinging swords' - makes it possible to alter the pressure of the water from fore to aft under sailing. In other words to steer in this way, and when the vessel is put on course, maintain the course by equalizing the pressure of the water on the fore and aft of the vessel. The new construction works traditionally, so far that vessel and keel skeg works as they have always done."

[ img - YDS-dinghy.gif ]
bow-centerboard   +   a fixed keel   +   aft-centerboard
cite-2:
"As soon as the wind fills the sail, and the aft fin is lifted, the fore fin accordingly will be a falling center for the swinging of the stern until it stands up against the wind.
Contrary - if the aft fin is down, and the fore fin is lifted, then the stemn will swing into lee, and the wind will blow into the aft.
At any moment and from any position, the swinging can be brought at bay. in other words, the presure of the wind at the sail and the presure of the water on the hull and the keel can be balanced."

Research and test by Y.D.Stenild in Denmark 1986:   "Sejlads på en anden måde" - ISBN 8774 661 159
[ img - anden-maade4.gif]

Balanced side-sliding with a Catamaran

photo of Dirch with his DIPPING steer-paddle, sailing his catamaran on the Carnon River in Cornwall.  > > > 
[ img - dirch.jpg ]

Some pacific double canoes employ the same principle as the Guara-rafts - they are using a handheld paddle for steering.
as Dirch explain: he is NOT TWISTING the steer oar, as they do on the Viking ships, the pacific sailors are holding their paddle on leeward side of one of the hulls, lowering or lifting it to BALANCE THE SIDE-SLIDING of aft-end in relation to for-end.
The paddle itself keep to the boat pressed by water - just as every lee-bord does.

Please note:
This last example indicate, that it is the AFT Guara as is important. With the aft you can controll the pointing.
Under normal sailing ahead, the bow is pressed into the sea and therefor hindred in side-sliding. Why fore-end don't need any Guara, except for static turn.
That no Guaras needed in extreme for, seems in conformity with the old drawing of admiral FE Paris 1841

The four testimonies - respectively from two rafts, a dinghy and a catamaran - show the same empirical result:

I):   Jorge Juan and Antonio Ulloa describe this very exactly and too show us a drawing of a indigeneous raft.

II):   Emilio Estrada placed his six Guaras as pairs along the central log, and when lifting up a Guara /centerboard for or aft, that end of his craft lost its hold in water and slided sidewards with the wind.

III):   Stenild in the same way balanced a dinghy - extending the natural keel with a centerboard for, and one more aft - and then throw away the rudder.
Lifting or lowering the Guaras (in the centerboard-version) in bow and stern - the side-sliding was balanced.

IV):   Dirch with his handheld paddle confirm the phenomenon, employing the same principle - balancing the side-sliding (without need to twist the paddle).

Guara steer system in Asia

under our way through an ocean of information, we have discovered that Guaras /daggerboard steering too is known in both the island of Taiwan and in area of Vietnam for use on their bamboo- rafts - and both claim to have got the daggerbord-steering from China.
   ref-1:   Cheng Kung University: A brief history of the Evolution of Taiwanese Rafts
   ref-2:   UNESCO:
Asian shipbuilding technology
The only reason why this papers are known by us is, that the author too has written in English language.
In none of the asian cases we have been able to decipher anything more around asian Guara-lore.
This references to Asian rafts we have got from the book of P.J.Capelotti: Sea Drift.
There is no evidence as indicate that Gyara-system has been known outside Asia and South America.
[ img - seagoingChineseRafts04.jpg ] [ img - Taiwanese-raft-model.jpg ] [ img - Taiwanese-draft.gif ]
Inevitable such information bring us to ponder over, if there had been Chinese contact across the Pacific Ocean prior to the famous admiral Zheng He who 1421 "discovered the world". We expect that china still keep documentation, as not has been translated and published in the western hemisphere around the voyage of their admiral then.

A helmsman can balance the side-sliding. Drifting a boat he always has known
[ img - scale.gif ]

The empirical theory of BALANCED side-sliding

We can make our raft point where we want by dipping the Guaras in AFT in balance with those FOR
= We are controlling the leeway of both ends independently

Balance of side-sliding is a theory as seems serviceable in all cases and for every floating sail vessel - rafts as well as boats, monohulls and multihulls.
The four reports all explain, that on a vessel sailing with the wind comming in over the side (beam - broad or close reach), we can balance the leeway of bow and stern independtly, by setting down Guaras.
Balancing the leeway between for and aft end is the way to control the pointing of our vessel.

Animation of a static turn - with wind abeam
[ img - balsaturn.png + balsaturns.gif ]
If we lift the front Guaras, the wind will press on the vessel and slide the bow sideways, while the raft or the dinghy is pivoting around the submerged aft Guaras as a hinge
- the craft will turn until the stern is pointing against the wind. Then the craft is ready to hoist sail and sail off.
Otherwise, if we lift up the aft Guaras /daggerboard /centerboard, the stern will side-slide and the craft (here the dinghy) will now turn up her bow against the wind.

[ img - dinghy.png + dinghys.gif ]

Of same reasons why a rudder is placed aft on the hull, the aft Guaras are the most useful for steering a raft: the bow is kept fixed by the bow-wave.
Lifting the aft fin (Guara) the stern will give more leeway and slide away = the boat will luff up.
Lowering the same aft fin will give us less leeway and our craft will bear away.

The balanced leeway is the reason why the first observations 4-500 years ago of the manoeuvrability of balsa rafts all told us, that these South American balsa rafts were able to sail out in the morning and return to same site on the coast in the evening (what not always was possible for the European vessels). But how that steer-system worked, was not analyzed.

What the old croniclers neither told us was, that a balsa raft steered by Guaras in-line could have some difficulties running for the wind, if not plunging down suficient AFT Guaras. But that problem we know from our monohulls, that by running we must let the sail draw and not push against the hull. That theme we will treat in a separate chapter. running for the wind

Examples of similar physic balances:

[ img - 3-forces-k.gif ]
A balanced sidegliding isn't something special for South American rafts. We can see the same constalation balance of 3 forces on a schooner or an eel-drifter, where we can influence on the sail direction (sidewarts) by adjusting the wind-press between mizzen and foresails.

There are hard-core sailors as declare, that they can sail their boat without a rudder - by 'playing' with their sails only.

[ img - 3-forces-s.gif ]
[ img - seesaw-2.gif ]
On a steelyard scale we can tilt the lever as we will, by changing the load or move the load along.
That is a balance between 3 forces on same line.
And that is what we are doing on our craft.
[ img - steelyard.gif ]
Of course we know, that the expression 'IN-LINE' not is correct: A scale is supported a little bit over the lever arm - and the CE-center of a sail is a little to leeward side of the center line of the vessel, whereas the CLR a little to windward of a heeled sail craft.
- and that is exactly what make the things work.

A working method employing balanced side-sliding

An eel-drifter is a flat-bottomed fisher boat, as work drifting sideways, hauling a drag-net along the sea bottom.
Having more masts and sails, the trick is to control their drift balancing by their sails - as indicated earlier.

The same way of fishing: hauling a trawl along the bottom while drifting slowly sidewarts was too used in the shallow lagoons along the southern shore of the Baltic sea.

[ img - eel-drifter.jpg ]

Two CONCLUSIONS of balanced side-sliding:

A Guara-raft sails rudderless - simply because she has no rudder
- and she abide the same rules as any other rudderless sailor on the sea -

By use of your bow and stern Guaras, you can dominate the pointing of your vessel
- and if your sail (or sails) is adjusted for that pointing, you will sail -
For the Skipper as is planning more ahead and a level above

[ img - weathercock.gif ]

The WEATHERCOCK principle

With centre of Hydraulic Resistance as pivot point your sail-vessel will blow to leeward

as well as you can hang a picture slant, you can point your boat !
You decide the hanging point - or where the hold in the water shall be !
[ img - slant-picture.png ]
- and the gravitation - respectively the wind will do the rest -

[ img - CLR5-star-33.gif ]
The common center of the Guaras make the hold in water
Weathercock raft with only four Guaras:
A raft with sail is out of control, until we plunge down a Guara/daggerboard
and here we will show what what a NORTHERN wind will do, if we plunge-down into the outermost cracks between trunks.

#1):       with Guaras plunget in both aft corners and a northern wind blowing - the raft will react and pivot around the blue-star-marked point between the two Guaras while mast and sail drift leeward - ready to take off running with course against South.
#1):[ img - raftS2.png ]
#2):[ img - raftE2.png ]
#2):       If we plunge in port Guaras both for and aft, the raft again will pivot around its new point between the two daggerboards and sail/mast go leeward - subsequent the raft will point against East with wind abeam on port side.
[ img - pahi63.gif ]
A side leap to Guara steering on oceangoing Catamarans:
#3):[ img - raftNW1.png ]
#4):[ img - raftNW3.png ]
#5):[ img - raftNW.png ]
#3, #4 and #5 show that with a Northern wind we wil have similar options for a Nord Western pointing. Each Guara will give a hold in water, but is too a waterbrake for headway.
What is best for actual raft in actuel situation skipper must find out.

#6):
[ img - raftstars.png ]

#6):       If we study the symmetry in our four Guara slots, the above examples show us, that we without greater problems can move or create pivot point all the way around the mast and all over the raft, as demonstrated by stars.
And still more Pivot points are possible, if some of the Guaras only are plunget in partial.

After setting the Guaras, the raft get hold in water and will turn just like a weather-cock around its pivot point ready to go ahead on a new course.

A next step could be to adjust your sail for that pointing you have choosed, and about sails for rafts we explain here.

 

A conclusion:
You can control the pointing of our raft all the compass around - with your Guaras alone
- and you are not limited to use Guaras along center-trunk -

What the past generations tried to tell

A modern explication of
what the old South Americans did

A Guara steer-system work only with the combination of wind on sails against the hydraulic resistance of underwaterbody

[ img - CE4star-37.gif ]
The CE = Center of Winds Effort is on a square sail the center of the canvas
Guayaquil, Ecuador 1841
The drawing was made by the french lieutenant, later admiral François-Edmond Pâris
is our technical most detailled of old sketches, and seen in the light of his later career we feel no reason to doubt of its reliability
[ img - balsa1841+.jpg ]
The semicircle of CE = Center of Effort for a lonely square sail is transfered to the old drawing
- and seems to pass just over the front Guara-group.
[ img - semic.png ]
[ img - semicircle1841.jpg ]

With reference to this old french drawing from 1841, we with three simple sketches can demonstrate, that what they did on a raft was to move the center of hydraulic resistance between for and aft.
That has as consequence, that the vessel will react as the rule says: the wind will blow and our craft will turn, until the centre of wind is directly downwind from the actual pivot-centre, defined by the position of the Guaras - and we have got a new pointing.

[ img - CLR5-star-33.gif ]
The hold in water is normaly called CLR = Center of Lateral Resistance

[ img - Guaras-FF.gif ] [ img - Guaras-AF.gif ] [ img - Guaras-AA.gif ]

In both the raft and the dinghy case named before, we were manipulating = changing the shape of the underwater body and in this way we controlled the position of Center of Hydraulic Resistance - and with that the pointing of the vessel.

Nevertheless, the old French drawing give us more information. There are reasons to note the place of formost Guara-group is just in front of mast and not in the bow. That is a place as seems placed just under where the sail center CE can be moved in its half circle.
That place has as consequence that the Guaras front of mast not will contribute much to the pointing of the raft - they are to consider more as a keel-arrangement. On the other hand, the need for front Guaras to steer isn't great; while a sailing ahead, the raft will press her bow into the sea and side-sliding of bow will be hindered.
It is the aft Guaras as have the job to point the raft - and that is in full accordance with the theory expressed of 'balanced sidesliding'.

The common rule for any sail-vessel:
The wind will blow the vessel leeward of her hold in water!
and thus define the pointing of the craft

- and that is what the greek deities Zephyr and Poseidon together try to explain here:
[ img - anden-maade-D.gif ] [ img - anden-maade-A.gif ] [ img - anden-maade-B.gif ] [ img - anden-maade-C.gif ]
Seen in a cross view with wind abeam, it is easier to accept, that the Centre of Wind for sail /mast is clearly blown leeward of the Centre of Hydraulic Resistance of the hull.
- and behold, a boat will heel the centre of wind more out, but a wide-beamed raft don't need to heel - and neither does.

sail dinghy with gaff rig
[ img - CE+CLR+dinghy.gif ]
viking replica Kraka
[ img - CE+CLR+kraka.jpg ]
raft with her Guaras
[ img - CE+CLR+raft.gif ]

- but seeing the last rightmost picture of a raft, we could ask, what will happen if instead along the central trunk, the Guaras was thrusted down in the outmost luff position ?
- and the answer is, that the "weathercock" will stay more stable.

[ img - weathercock.gif]
this is why we call it the "Weathercock Principle":
the weathercock will always keep a stable pointing against the wind

NOTE two things:
A): That is right, that more Guaras plunged in give more keel and theoretically less leeway - if you need that,
- but more Guaras down too give a loss in headway and weaken the sensibility of steering by Guaras. Therefor, if you can sail alone with your long straight side-trunk as keel and few Guaras down to steer - then do that.

B): Large distance from pivot point of weathercock to its centre of wind, do the same as large distance from the Hydraulic Centre of the Guaras to the centre of sails - that bring less swing, and less oscillation of the weather-cock as well as less oscillation of the raft when gusts come.

too many versus too few

Don't kill your Guara steering

Do as the old investigations indicate: plunge in a pair of Guaras in front end, and a pair more in aft end - and use those two most extreme pairs for steering.
If your raft is well trimmed - that will do it.

Note the observation from Dirch: when sailing ahead, only aft Guaras or dipping paddle is needed for steering. Ref:
Tangaroa 1965 passed the dangerous Tuamotu Archipelago of French Polynesia by employing 3 Guaras only. One in front - and two aft.

Statement:
Guaras is a steer system and not a keel supplement

The "keel" of a raft is the long and straight side-trunk, as give the necesary high lateral hydraulic resistance.
If you absolutely need more keel to beat higher to the wind or something like that, then you could add a lee-board, a centerboard or a luffboard by plunging a board down in the steer-neutral midship zone in front of mast (just where the CE pass over in its orbit around the mast). First a luff-board before a center-board before a leeboard, because of the usefull stabilizing wind-vane-effect.
Then not more.
Around the many broken Guaras as we have heard about then look at this proposal.

One thing is Guara-slots, but DON'T fill up your raft-bottom with Guaras ! Any fin plunged down under a craft will of course reduce leeway, but too reduce headway. It is astonishing how much a surplus of long and deep fins as Guaras can brake the headway.
Furthermore you may "overkill" the steering.
Too many Guaras plunged down will reduce the impact from your steer-Guaras, reducing their influence on the common center of hydraulic resistance.
And we suspect that phenomenon to be the killer of Kontiki2 expedition 2015. They couldn't steer back to SouthAmerica and vanished in the South Pacific.

Hypothesis - as still miss empirical evidence:
Too many Guaras plunged in as keel-supplement will be a hindrance for steering

Overcrowded beneath was the supposed killer of the Kontiki2 expedition of 2015
the crowded beneath of the Manteño raft 1996
[ img - manteno3.jpg ]
they happend to break around 10 Guaras
[ img - Tangaroa2-guaras.jpg ]
underneath Tangaroa2-2006
- no comments given

If you overcrowd your raft bottom with many Guaras,
you will reduce the sensibility of your steering and eventually kill it -
That is still the COMMON center CLR of all those Guaras, as decide and define the pointing -
Rudderless is a sport for the most hard-core

The rules for "rudderless sailing" is valid too for rafts

.
[ img - Rudderless_Sailing_by_Joel_Brand.gif
A rudderless sailor tilting his centerboard to move his hydraulic center more aft.

A raft is sailing "rudderless" - simply because she has no rudder - and the principles of "rudderless sailing" is a theme for much writing of books, manuals and at internet.
Link to some writings around rudderless sailing.

The hull of the raft itself skipper has to accept with its strong and weak build-in qualities - but he can operate his Guaras and adjust the sail

The center of water resistance will under all the sailing be in balance with the forces from wind - in every moment. This balance is what define the pointing of the craft, which too means, that the only way skipper has to correct the pointing of his Guara-raft is by changing the underwater-body = adjusting the Guaras - or move the center of sails, if rigging permit that.

A Guara-raft sails rudderless - simply because a raft has no rudder
- and she abide the same rules as any other rudderless sailer on the sea

post scriptum:

If you still are in doubt, what a rudderless sail craft can do - then ask a wind-surfer.   He knows
[ img - ce+clr.gif ]
Sailors in water (not wheeling on land nor skating on ice) have to calculate with leeway

The inevitable Leeway

The art of sailing is to beat against the wind.

Wind abeam on a vessel give leeway, that know every seaman, and skipper has to calculate with leeway, as he only can escape when running downwind. That phenomenon is applied for every craft - perhaps with exception of submerged submarines, wheeled land-sailers [ img - beach-sailer.jpg ]   and   skated iceboats.[ img - iceboat.jpg ]
The captain on the cruise liner know it, and that is why his ship is supplied with thrusters for and aft to compensate. Too the freight skipper know it. He has only one propeller and one rudder, and therefor he is very careful, when he is entering slowly in a narrow harbor entrance with the wind across. He probably will not do that without a tug-boat for assistance.

Rule for calculation:
The real course is the result of steered course with leeway added
(whatever leeway is due to wind or current)

Sail-ships generally are trimmed for wind abeam, but as said: they can't escape leeway. In some special situations we directly make use of this broadside drift - as for example the eel-drifter as the name indicates work drifting sideways, or when a square sailor 'heave to' - make use of her high lateral resistance to to wait with sail hoisted - wait drifting slowly.

Wind abeam is the "Mother of all leeway" - and that is why a sail-vessel always seems pointing higher to the wind than the true course.
When we are navigating a sail boat, we have to calculate with leeway, and the side-drift depends alone of the strength of wind and the area of sail and hull against the lateral Hydraulic Resistance. The stronger the wind, the more leeway - and of course: more sail more leeway. Leeway simply is a result of the wind's broadside forces against the Lateral Hydraulic Resistance of the hull.

Every sail-vessel hold a LOW forward resistance, in combination with a HIGH lateral ditto
- and wind abeam - in spite of the HIGH lateral water resistance - give leeway.

On a square-off raft the common expresions are a bit confused. On such a raft as sometimes use the one corner as stem, we could have doubt around where the vessel is "pointing" - along centerline or along the diagonal?
Nevertheless, a Guara-raft you can "point" as you will. If the sail is adjusted for diagonal sailing a skipper with a "square-off"-raft can sail along a diagonal, that is not the problem - but he still have to calculate with some leeway.
That confusion around "diagonal sailing" versus leeway seems a part of the problem on last raft raid 2015.

[ img - afdrift+styret-kurs-A.png ]
a pointed raft can sail on as pointing - along a centerline
+ with a few degrees of leeway
[ img - afdrift+styret-kurs-B.png ]
a square-off raft can sail along the diagonal
+ added the same few degrees of leeway
but is loosing sail-speed crabbing half sideways
Independent of pointing, wind abeam give leeway.
[ img - afdrift+styret-kurs-C.png ]
It seems as a logical consequence of the two first figures, that a Guara-raft should be able to adjust her pointing to be in accordance with her true course - but THAT IS WRONG!
Skipper has to point his raft + and then add the leeway. Only by direct downwind sailing he can escape that.

Leeway is not directly influenced by the forward heading, because that is the effectiveness of the sail as have the task to split up the wind force in a lateral and a foward directed force, and then push with maximum force ahead against lowest resistance.
Indirectly a reefing or other reduction of sail reduce the force from wind - and thereby reduce both headway and leeway. But due to the wind on hull and hut not is reduced, the craft in her total get relative more leeway sailing reefed. And that statement has as consequence, that a big superstructure on a raft give a big leeway.
The challenge to find a LOWEST forward hydraulic resistance of a hull, was for example the main objective for the Norwegian tank tests
- but they lost this advantage by confusion of what course they actually sailed - versus that course they thought they really pointed with their rafts.

Many types of vertical boards exist

The family of Guaras:
Dagger-boards, centerboards and Lee-bords

Everybody can run a boat for the wind - and to sail with wind abeam is neither difficult
"The art of sailing is to beat close hauled to the wind"

That is what will classify to excellence the skill of skipper and his sailing craft

A leeboard explication
[ img - wind+vand.jpg ]
CE=Center of effort versus CLR=Center of Lateral Resistance

Leeboard - the family to Guara

The Guara /daggerboards was totally unknown for the Europeans. The fun is that similar system - as cousin to the Guaras - has been used several hundred of years in the northern Europa in the form of leeboards.

The Dutch did not invent leeboards. They saw them being used in the Far East during their discovery voyages in the early 1500s. In China they have a documented experience of more than one thousand years.

The result of this learning we saw on the Dutch rivers, canals and inland waterways, the German, Frisian and Waddensea coast up to South in Denmark. All over, up and down the coast of East England, on the rivers Thames and Humber we had these 'daily work horses' in form of flat-bottomed and shallow drafted boats as Sloop, Barge, Keel, Ewer, Tjalk, Seascow, Botter, Kaag, Kahn, Evert, Curonian et cetera - all without a keel. Ewen far away, on all the shalow lagoons along the Baltic coast of Germany and Poland up to the Curonian lagoon between Lithuania and Kaliningrad, they sailed with their flat bottom and leeboards.

Even if they perhaps will do better with leeboard
ALL the pictured flat-bottom vessels can beat against the wind.

In China they knew the Guara-steering - and from China came the lee-board to Europa - but the Guara-steering not
Song is Contemporary with the South American rafts
[ img - SongJunk.jpg ]
13 century junk drawn with two lee-boards

[ img - 2-thames_barge.jpg  ]
Thames barge resting by low tide
[ img - 1-thames_barge.jpg ]
fore and aft rigged English Thames Barge
[ img - 3-humber_keel.jpg ]
Humber Keel recognizable by its square sail
[ img - 9-old_curonian.jpg ]
Curonian fishing boat
showing her shallow draft
[ img - 5-ribe_evert.jpg ] [ img - evert-i-kran.jpg ]
Danish Waddensea Evert
will show her flat-bottom
>>Mouse-over<<
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Danish Evert landed in Waddensea
[ img - 4-plattbodenschiff.jpg ]
German flat-bottom resting on waddensea shore
[ img - Trouwe-Hulp-droogvallen.jpg ]
Dutchman landed at a sunset shore
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Dutch Lemsteraak showing how a luff board will heel out of water
All the pictured vessels ware able to beat to the wind- even if some of them, but not all did it better with lee-board

Unlike the Guaras, the leeboard is mounted outside the hull and normally one on each side - obvious for not to affect integrity of neither hull nor hold - and they are placed midship, very central on the side of the 'Center of Effort' of the sails, for not to disturb the effective trim of their crafts, as are steered by rudder.

LEEBOARDS were principally used to stabilize the course by reducing side-sliding of flat-bottomed sailboats, as couldn't have any natural keel - mainly because they needed to sail, land and beach in shallow waters or on riverbed by low tide. Up to one compass point = 6 degrees closer to the wind, than the same boat with leeboard up - is told us.

But the sailing people learned that leeboards could be a great help as pivot-point turning through the windeye under a tack. And with a leeboard hanging several feet below the ship-bottom, they had too a good sound-warning against banks and ground, when sailing in shallow waters.

[ img - hull of Humber keel.jpg ] [ img - humber_keel+leeboard.gif ]
The Humber Keel with her long and deep slap side was equipped with leeboard, but not because of need for keel - the slab side did it, and specially when loaded down. It did it too well, that she was difficult to turn in narrow waters. Therefor the main reason for leeboard was to get a turnpoint for the tack - and of course a sonic warning for low water, hanging one yard under the bottom.
The Humber Keel is well balanced and has her mast rather in front to match the forward moved CLR = Center of Water Resistance when sailing. The sideboard was as named mostly for turning purpose. Had the mast not been moved ahead, the sideboard had worked better behind the mast moving CLR backwards.

We have never heard of more leeboards mounted on same side; and therefor the Europeans never discovered the Guara steering qualities: to balance the side-sliding between for and aft - but in China they did.

Somewhere we found an old thumb-rule for dimensioning of leeboards,
saying that the underwater size of this board should hold 3-5% of sail area
- but saying nothing around shape, nor length nor breadth -
And the ship development went on

From leeboard to centerboard

The outside leeboards were used in centuries, until our evolution in ship-technology was able to construct safe and reliable wells inside a hull, what happend around 150 years ago. Then leeboards in some yacht-designs entered from both sides and joined in one single board in center - called centerboard of course - more as ONE adjustable keel and easier to handle than TWO leeboards on same boat. Later on the centerboard too was equipped with a counterweight.
Leeboards are hinged and centerboards too, whereas a daggerboard is a board pushed down in a sheath like a dagger, and has therefore to be of manageable size and weight - why only used in smaller sailvessels. Guara is mostly to compaire with a daggerboard.
Inside her well for living eels this eel-drifter has mounted a centerboard.

Neither here, we have never seen a boat with more than one centerboard - other than the trial-dinghy named.

A last word to Heyerdahl

An observation from Egyptian tombs and pyramids

Handling a Thor Heyerdahl theme, we inevitable - by the RA reed rafts - are brought in contact with the ship-lore of ancient Egypt.

Around Nile seafaring

The Nile river is and has allways been used for transport of goods along its length, and this natural and simple water transportation system grew a key element in the development of the ancient egyptian civilization, and was therefore too the base for development of water crafts - their boats.

As a natural navigation channel and river road along all Egypt, the Nile was favoured by wind and stream. The waterway is known for its special conditions: row and drift downwards with the current against North - and using the steady North or North-Eastern trade wind to thrust the boats upstream against South. And this phenomenon probably in some way has been determinant conditions for the creation of their early sail culture on Nile and Red Sea.
Thor Heyerdahl
I have no idea if the model of origen for the reed rafts of Thor Heyerdahl was of same kind, but they doesn't look like the boats from the pyramid pictures, nevertheless his reed raft is told to come from the Upper Nile of Sudan. And his system of double steeroar looks like the oldtimers - but the steer oars at RA II are mounted with tillers as we can't see on the old paintings. Neverthemind - who knows - - - Heyerdahl too discovered his Guarasteering after his Kon-tiki raid.
Thor Heyerdahl sailed mainly his reed rafts downwind, when crossing the oceans, and with two steeroars aft, then he at least had moved backwards the CLR - and furthermore because the RA2-photo show the mast relatively ahead, then he cleverly too stabilized his sailing moving the windcenter CE ahead.

Perhaps if he had used the Pharaohnic principle with a short pool to sustain the shaft of his long steer-oar, Thor Heyerdahl navigating Kon-tiki in 1947 could have used less forces by dipping the same oar than to angel it, press it out of centerline, as he did. But he didn't know that then, because he had still not learned about the function of his Guaras.

[ img - ThorHeyerdahl+styreaare.jpg ]

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Lima - August 2018